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Distributed Cutting Plane Method Via Sample Point consensus

IEEE Transactions on Automatic Control 2025年

作者： Zhong, Tianyi Angeli, David Imperial College Control and Power Group Electrical and Electronic Engineering Department LondonSW7 2AZ United Kingdom University of Florence Department of Information Engineering Italy

This paper considers a general setup for the constrained convex optimisation problem over jointly-fully connected time-varying networks. We propose a novel cutting plane-based method that embeds a proximity-based consensus scheme for solving this (potentially non-smooth) optimisation problem. The consensus mechanism allows agents to select the same sample point and therefore reconstruct the centralised cut individually. Under convexity, we prove that agents' sample points converge to the optimal set of the global problem. Numerical tests show the performance of the algorithm. © 1963-2012 IEEE.

关键词： consensus algorithm

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A consensus-based cooperative Spectrum sensing technique for CR-VANET

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PEER-TO-PEER NETWORKING AND APPLICATIONS 2021年第2期14卷 781-793页

作者： Zargarzadeh, Sahar Moghim, Neda Ghahfarokhi, Behrouz Shahgholi Univ Isfahan Fac Comp Engn Esfahan Iran

Internet of Things (IoT) is expected to empower all aspects of the Intelligent Transportation System (ITS), the main goal of which is to improve transportation safety. However, due to high demands by the increasing number of associated vehicles, the allocated bandwidth of ITS is inadequate. Cognitive Radio (CR) technology can be used as a solution for this high demand level. In CR, the pre-allocated spectrum bands are sensed to find the existing holes, caused by the absence of primary users. Cooperative spectrum sensing is an efficient tool for the detection of free spectrum bands that increase the probability of correct detection. In this paper, a distributed cooperative spectrum sensing technique is proposed using the consensus algorithm which is a distributed data aggregation mechanism whereby each vehicle combines the results received from its neighbors' spectrum sensing. The combined results are repeatedly shared and combined such that all vehicles reach the same results. In vehicular networks, due to the vehicle's movement, the number of its neighbors changes dynamically. Therefore, considering the vehicle's mobility is essential in the spectrum sensing process. The consensus algorithm which is a data aggregation method is used to increase the probability of correct detection, and thus to reduce the number of collisions in the spectrum acquisition process. In our method, each vehicle accurately selects a number of its neighbors dynamically, and involves them in the decision-making process. Moreover, separate weights determined based on the entropy of their information are assigned to the sensing results of the selected neighbors. In this way, even if the vehicles are affected by fading or shadowing, they can make more accurate decisions using the sensing results received from other vehicles. The simulation results of the proposed method show that it increases the probability of correctly detecting free spectrum bands as well as convergence speed.

关键词： consensus algorithm Cooperative Spectrum sensing Cognitive radio Vehicular networks

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An enhanced second-order-consensus-based distributed secondary frequency controller of virtual synchronous generators for isolated AC microgrids

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ENERGY REPORTS 2021年 7卷 5228-5238页

作者： Wan, Xiaofeng Ding, Xiaohua Hu, Hailin Yu, Yunjun Nanchang Univ Sch Informat Engn Nanchang 330031 Jiangxi Peoples R China Jiangxi Univ Sci & Technol Sch Elect Engn & Automat Ganzhou 341000 Peoples R China

Virtual synchronous generator (VSG) control is a promising control method in microgrid (MG) for the inertia support characteristic. However, the VSG inherits the oscillation feature of synchronous generator (SG), thus the active power and frequency oscillation may be observed when VSG control is applied. In MG, the oscillation may cause the unreasonable dynamic active power sharing among VSGs. Subsequently, the VSGs are prone to overload and even unstable, and the existing works based on consensus control cannot suppress the oscillation effectively. In order to tackle this problem, this paper proposes an enhanced second-order-consensus-based distributed secondary frequency controller by introducing the active power second-order consensus control, and reveals the oscillation suppression capacity of the second-order consensus algorithm in depth. Since there is no specific control requirement for the second-order variables, i.e., the change rate of active power and frequency of MG in steady state, the proposed controller can be simplified by replacing the integral control of second-order variables with the proportional control of first-order variables, i.e., active power and frequency, thus the communication data volume will not increase comparing to the traditional first-order-consensus-based controller. This paper also provides a small-signal model of MG with the proposed controller to evaluate the system dynamic performance and design the parameters. Finally, the simulation results verify the effectiveness of the proposed controller. (C) 2021 The Authors. Published by Elsevier Ltd.

关键词： consensus algorithm Distributed secondary control Microgrid (MG) Multiagent system (MAS) Power oscillation Transient performance Virtual synchronous generator (VSG)

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On the Inconsistency of Estimation with Uncertain Models 58

On the Inconsistency of Estimation with Uncertain Models

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58th Asilomar Conference on Signals, Systems and Computers, ACSSC 2024

作者： Uribe, Cesar A. Hare, James Zachary Kaplan, Lance M. Jadbabaie, Ali Rice University HoustonTX United States Devcom Army Research Laboratory AdelphiMD United States Massachusetts Institute of Technology CambridgeMA United States

ISBN: (纸本)9798350354058

We study the hypothesis testing problem where an agent seeks to select a hypothesis from a finite set Θ, based on a sequence of i.i.d. observations of a random variable Xk∼ P∗ fork≥ 1 with unknown distribution P∗. Each hypothesis θ∗∈Θ states that Xk∼ Pθ. The objective is to find a hypothesis θ∗ such that θ= arg minθ∈Θ DKL(P∗|| Pθ). However, the set of hypotheses {Pθ} is partially known, where only a finite number of observations are available for the random variables Ysθ∼ Pθ with θ∈ Θ. We show that contrary to classical Bayesian approaches, the obtained estimator will not be consistent, and the aggregated log-likelihood ratios will converge in distribution to a Gaussian distribution even when k→∞. Our result states that estimators with uncertain likelihoods will not concentrate on the true hypothesis. There is a strictly positive probability that the belief in a suboptimal hypothesis is maximal. © 2024 IEEE.

关键词： consensus algorithm

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Improved Space Bounds for Subset Sum 32

Improved Space Bounds for Subset Sum

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32nd Annual European Symposium on algorithms, ESA 2024

作者： Belova, Tatiana Chukhin, Nikolai Kulikov, Alexander S. Mihajlin, Ivan St. Petersburg Department of Steklov Institute of Mathematics The Russian Academy of Sciences Russia Neapolis University Pafos Paphos Cyprus JetBrains Research Paphos Cyprus

ISBN: (纸本)9783959773386

More than 40 years ago, Schroeppel and Shamir presented an algorithm that solves the Subset Sum problem for n integers in time O∗(20.5n) and space O∗(20.25n). The time upper bound remains unbeaten, but the space upper bound has been improved to O∗(20.249999n) in a recent breakthrough paper by Nederlof and Węgrzycki (STOC 2021). Their algorithm is a clever combination of a number of previously known techniques with a new reduction and a new algorithm for the Orthogonal Vectors problem. In this paper, we give two new algorithms for Subset Sum. We start by presenting an Arthur-Merlin algorithm: upon receiving the verifier's randomness, the prover sends an n/4-bit long proof to the verifier who checks it in (deterministic) time and space O∗(2n/4). An interesting consequence of this result is the following fine-grained lower bound: assuming that 4-SUM cannot be solved in time O(n2−Ε) for all Ε > 0, Circuit SAT cannot be solved in time O(g2(1−Ε)n), for all Ε > 0 (where n and g denote the number of inputs and the number of gates, respectively). Then, we improve the space bound by Nederlof and Węgrzycki to O∗(20.246n) and also simplify their algorithm and its analysis. We achieve this space bound by further filtering sets of subsets using a random prime number. This allows us to reduce an instance of Subset Sum to a larger number of instances of smaller size. © Tatiana Belova, Nikolai Chukhin, Alexander S. Kulikov, and Ivan Mihajlin;licensed under Creative Commons License CC-BY 4.0.

关键词： consensus algorithm

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Robustness Analysis of Zero-Knowledge Proofs Technique using Subset Sum Problem 7

Robustness Analysis of Zero-Knowledge Proofs Technique using...

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7th International Conference on Contemporary Computing and Informatics, IC3I 2024

作者： Sah, Chitranjan Prasad Kaur, Manjot Singh, Gurwinder Chandigarh University Department of Computer Science and Engineering Punjab India Punjab India

ISBN: (纸本)9798350350067

In this paper, security mechanism called zero knowledge proofs has been defined using subset sum problem. We have used subset sum problem for robustness analysis of zero-knowledge proofs technique in cryptography. The upper bound of subset sum problem given by meet-in-the-middle algorithm is more efficient than Nïve algorithm, so we have used meet-in-the-middle algorithm for analyzing robustness in comparison with discrete logarithm problem used by Henry. Also, we have computed covariance between asymptotic notations of meet-in-the-middle and the discrete logarithm problem is employed in the technique of zero knowledge proofs which is positive. Positive covariance between them shows that relationship between input variants used by both functions is similar in behavior. Both functions are growing in same direction and our used function (meet-in-the-middle) is growing faster than Henry (Discrete Logarithm). © 2024 IEEE.

关键词： consensus algorithm

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An algorithmic Meta Theorem for Homomorphism Indistinguishability 49

An Algorithmic Meta Theorem for Homomorphism Indistinguishab...

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49th International Symposium on Mathematical Foundations of Computer Science, MFCS 2024

作者： Seppelt, Tim RWTH Aachen University Germany

ISBN: (纸本)9783959773355

Two graphs G and H are homomorphism indistinguishable over a family of graphs F if for all graphs F ∈ F the number of homomorphisms from F to G is equal to the number of homomorphism from F to H. Many natural equivalence relations comparing graphs such as (quantum) isomorphism, cospectrality, and logical equivalences can be characterised as homomorphism indistinguishability relations over various graph classes. The wealth of such results motivates a more fundamental study of homomorphism indistinguishability. From a computational perspective, the central object of interest is the decision problem HomInd(F) which asks to determine whether two input graphs G and H are homomorphism indistinguishable over a fixed graph class F. The problem HomInd(F) is known to be decidable only for few graph classes F. Due to a conjecture by Roberson (2022) and results by Seppelt (MFCS 2023), homomorphism indistinguishability relations over minor-closed graph classes are of special interest. We show that HomInd(F) admits a randomised polynomial-time algorithm for every minor-closed graph class F of bounded treewidth. This result extends to a version of HomInd where the graph class F is specified by a sentence in counting monadic second-order logic and a bound k on the treewidth, which are given as input. For fixed k, this problem is randomised fixed-parameter tractable. If k is part of the input, then it is coNP- and coW[1]-hard. Addressing a problem posed by Berkholz (2012), we show coNP-hardness by establishing that deciding indistinguishability under the k-dimensional Weisfeiler–Leman algorithm is coNP-hard when k is part of the input. © Tim Seppelt.

关键词： consensus algorithm

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An Improved 2-Approximation algorithm for the Rectilinear Steiner Tree Problem with Minimal Number of Steiner Points 4

An Improved 2-Approximation Algorithm for the Rectilinear St...

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4th International Conference on Applied Mathematics, Modeling and Computer Simulation, AMMCS 2024

作者： Li, Jianglin Wang, Wencheng Chen, Yinhua Zhang, Tongquan School of Mathematics and Computer Science Yunnan Minzu University Yuehua Street NO.2929 Yunnan Kunming650504 China School of Applied Technology Yunnan Minzu University Yuehua Street NO.2929 Yunnan Kunming650504 China

ISBN: (纸本)9781643685519

In this paper, we present an improved algorithm for the rectilinear Steiner trees problem with minimal number of Steiner points. Given a set X of n terminal points in the L1 plane and a positive constant L, it is asked to construct a Steiner tree T interconnecting of these n terminal points, with the length of each edge in that tree T is no more than L. It has been proven that this problem is NP-hard and there exists a 2-approximation algorithm in time O(n3). By using the strategies of the sweep-line algorithm and a leaf-deletion technique in a special forest composed of selected edges from a rectilinear minimum spanning tree on X, we propose an effective 2-approximation algorithm in time O(n log n). © 2024 The Authors.

关键词： consensus algorithm

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Secure Electronic Health Record Storage in the Cloud Based on Multiple Fragmentation and Reconstruction Using Blockchain with Cryptographic Techniques 4

Secure Electronic Health Record Storage in the Cloud Based o...

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4th International Conference on Ubiquitous Computing and Intelligent Information Systems, ICUIS 2024

作者： Mercy, W. Annabel, L. Sherly Puspha Kcg College of Technology Anna University Dept. of Cse Chennai India St. Joseph's College of Engineering Dept. of Artificial Intelligence and Machine Learning Chennai India

ISBN: (纸本)9798331529635

Data privacy is an important factor in cloud data storage. Still there are some security issues such as hacking that may take place with respect to data. In the existing techniques the time and cost consumption are more in computing and data storage. Data privacy is a challenging one against hacking and to avoid hacking data can be fragmented over multiple locations when storing and reconstructed while accessing the data. In the existing implementation single field query is used to access the Electronic Health Records (EHR). It will take more time to fetch the data and the fetched data also will be huge with some unwanted data. This paper proposes multi field skyline conditional query to access the accurate EHR data for minimizing the accessing time to improve the performance by implementing B+-Tree indexing and skyline query. Cloud data storage privacy also will be improved with Cryptography and Blockchain techniques. Secure Hashing algorithm (SHA 512), consensus algorithm and Smart Contracts are used for data integrity and fault tolerance mechanism. The possible goals include effective data storage and access, reducing security breach, storage overhead, avoiding hacking, enhancing data privacy. © 2024 IEEE.

关键词： B+ - Tree Blockchain Cloud Storage consensus algorithm Data Fragmentation Data Reconstruction Electronic Health Records Secure Hashing algorithm Skyline Query Smart Contracts

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Setting Targets is All You Need: Improved Order Competitive Ratio for Online Selection 24

Setting Targets is All You Need: Improved Order Competitive ...

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25th Conference on Economics and Computation, EC 2024

作者： Chen, Liyan Sun, Nuozhou Tang, Zhihao Gavin Institute for Interdisciplinary Information Sciences Tsinghua University China ITCS Key Laboratory of Interdisciplinary Research of Computation and Economics Shanghai University of Finance and Economics China

ISBN: (纸本)9798400707049

There is a rising interest for studying the online benchmark as an alternative of the classical offline benchmark in online stochastic settings. Ezra, Feldman, Gravin, and Tang (SODA 2023) introduced the notion of order-competitive ratio, defined as the worst-case ratio between the performance of the best order-unaware algorithm and the best order-aware algorithm, to quantify the loss incurred by the lack of knowledge of the arrival order. They showed in the online single selection setting (a.k.a. the prophet problem), the optimal order-competitive ratio achieved by deterministic algorithms is 1/φ ≈ 0.618, and left with an open question whether randomized algorithms can do better. We answer the open question firmly by introducing a novel family of algorithms called targeted value algorithms. We show that the task of online selection is as easy as guessing the optimal online benchmark. Specifically, we provide 1) an alternative optimal 1/φ order-competitive algorithm by setting the targeted value deterministically, and 2) a 0.732 order-competitive algorithm by setting the targeted value randomly. We further provide a 0.758 upper bound on the order-competitive ratio of our algorithm, showing that our analysis is close to the best possible, and establish an upper bound of 0.829 on the order-competitive ratio for general randomized order-unaware algorithms. © 2024 Copyright held by the owner/author(s).

关键词： consensus algorithm

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